Where: R = coefficient reliability
K = the number of the test scores
M = the mean of the test scores
S = the standard deviation of the test scores
According to Arikunto in Nainggolans’ Thesis (2009:25) the categories of
coefficient correlation are as following:
0.00-0.20 : the reliability is very low
0.21-0.40 : the reliability is low
0.41-0.60 : the reliability is fair
0.61-0.80 : the reliability is high
0.81-above : the reliability is very high
Scoring of Vocabulary
The test is multiple choice tests. There are about 20 queations for each cycle. In scoring
the vocabulary test, it is determined that the ranging from 0-100 by accounting the correct
answer. The correct is given 5 while the wrong answer is given 0 and by applying this
formula: